<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style lang="scss">
        .father {
            background-color: #ccc;
            .son {
                background-color: skyblue;
            }
        }
        
        .son {
            background-color: #c00000;
        }
    </style>
</head>

<body>
    <div class="father">
        父亲
        <div class="son">儿子</div>
    </div>
    <div class="son">庶子</div>
</body>

</html>